I am not going to write tutorial how and what you need to do in order to write module. If you want to learn this I am sorry but you are in a wrong place. Instead this is about the process that people who use Drupal should be using when thinking about developing new module. I was inspired but the article when should I create a new drupal module - it is very short and you may want to read it in full.Most of people who use Drupal to run websites they go through the same or similar steps when it comes to find module to provide new option. Please check diagram Drupal module decision and I bet you will find it very familiar with what you do or almost exactly what you do already - at least it describes the steps I usually take. I am glad that I came across this article and diagram - finally someone created proper flowchart that I will be using and sharing if neede. Good work.